Causes and consequences of increase in child survival rates: ethnoepidemiology among the Hmong of Thailand.

The Hmong "hill tribe" minority in Thailand has much higher exposure to factors usually associated with risk of child mortality (high fertility, low status of women, low education, less use of modern medical care for births, exposure to warfare, economic and physical disruption, and poor hygienic conditions) than the rural ethnic Thai population. Nonetheless, infant mortality has declined from over 120 per 1000 to under 50 per 1000 live births among both these populations in the past 30 years. The reason for the rapid increase in child survival among the Hmong appears to be better access to and more use of modern curative and preventive medical care associated with road construction rather than major changes in social or hygienic conditions. Conventional wisdom suggests that high fertility is both a cause and a consequence of high infant and child mortality and that parents will not reduce fertility until they see that mortality has declined. Most Hmong parents recognize the decline in child mortality and attribute it to better access to modern medical care. Most Hmong parents also say that, if they were starting to have children now, they would want to have fewer children. Fear of child death is infrequently mentioned as a motive for having more children, and the perceived decline in child mortality is rarely mentioned as a reason for reduced fertility. Most Hmong parents explain their desired family size in terms of economic conditions rather than perceived risk of child mortality. Results of this study suggest that fertility and child mortality can vary independently of one another and that major reductions in child mortality can be accomplished without waiting for major social changes (e.g., improved education or status of women) or major reductions in fertility.     

Pests controlling pests: does predator control lead to greater European rabbit abundance in Australasia?

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Increasing healthy eating vs. reducing high energy-dense foods to treat pediatric obesity

Objective: The objective was to compare targeting increased eating of healthy foods vs. reducing intake of high energy‐dense foods within the context of a family‐based behavioral weight control program. Methods and Procedures: Forty‐one 8–12 year‐old children >85th BMI percentile were randomly assigned to a 24‐month family‐based behavioral treatment that targeted increasing fruits and vegetables and low‐fat dairy vs. reducing intake of high energy‐dense foods. Results: Children in the increase healthy food group showed greater reduction in zBMI compared to children in the reduce high energy‐dense food group at 12‐ (?0.30 zBMI units vs. ?0.15 zBMI units, P = 0.01) and 24‐ (?0.36 zBMI units vs ?0.13 zBMI units, P = 0.04) month follow‐up. Parents in the increase healthy food group showed greater reductions in concern about child weight (P = 0.007), and these changes were associated with child zBMI change (P = 0.008). Children in the reduce high energy‐dense group showed larger sustained reductions in high energy‐dense foods (P < 0.05). Baseline levels of high energy‐dense foods (P < 0.05), parent food restraint (P = 0.01), parent concern over parent weight (P = 0.01) and parent acceptance of the child (P < 0.05) moderated child zBMI change, with greater sustained reductions in zBMI for children in the increase healthy food group for each measure. Parent zBMI change followed the same pattern as child changes, and parent and child zBMI changes were correlated (P < 0.001). Discussion: Focusing on healthy food choices within an energy restricted diet may be useful in family‐based weight control programs.     

Drivers of Inequality in Millennium Development Goal Progress: A Statistical Analysis

Background

Many low- and middle-income countries are not on track to reach the public health targets set out in the Millennium Development Goals (MDGs). We evaluated whether differential progress towards health MDGs was associated with economic development, public health funding (both overall and as percentage of available domestic funds), or health system infrastructure. We also examined the impact of joint epidemics of HIV/AIDS and noncommunicable diseases (NCDs), which may limit the ability of households to address child mortality and increase risks of infectious diseases.

Methods and Findings

We calculated each country''s distance from its MDG goals for HIV/AIDS, tuberculosis, and infant and child mortality targets for the year 2005 using the United Nations MDG database for 227 countries from 1990 to the present. We studied the association of economic development (gross domestic product [GDP] per capita in purchasing-power-parity), the relative priority placed on health (health spending as a percentage of GDP), real health spending (health system expenditures in purchasing-power-parity), HIV/AIDS burden (prevalence rates among ages 15–49 y), and NCD burden (age-standardised chronic disease mortality rates), with measures of distance from attainment of health MDGs. To avoid spurious correlations that may exist simply because countries with high disease burdens would be expected to have low MDG progress, and to adjust for potential confounding arising from differences in countries'' initial disease burdens, we analysed the variations in rates of change in MDG progress versus expected rates for each country. While economic development, health priority, health spending, and health infrastructure did not explain more than one-fifth of the differences in progress to health MDGs among countries, burdens of HIV and NCDs explained more than half of between-country inequalities in child mortality progress (R ²-infant mortality  = 0.57, R ²-under 5 mortality  = 0.54). HIV/AIDS and NCD burdens were also the strongest correlates of unequal progress towards tuberculosis goals (R ² = 0.57), with NCDs having an effect independent of HIV/AIDS, consistent with micro-level studies of the influence of tobacco and diabetes on tuberculosis risks. Even after correcting for health system variables, initial child mortality, and tuberculosis diseases, we found that lower burdens of HIV/AIDS and NCDs were associated with much greater progress towards attainment of child mortality and tuberculosis MDGs than were gains in GDP. An estimated 1% lower HIV prevalence or 10% lower mortality rate from NCDs would have a similar impact on progress towards the tuberculosis MDG as an 80% or greater rise in GDP, corresponding to at least a decade of economic growth in low-income countries.

Conclusions

Unequal progress in health MDGs in low-income countries appears significantly related to burdens of HIV and NCDs in a population, after correcting for potentially confounding socioeconomic, disease burden, political, and health system variables. The common separation between NCDs, child mortality, and infectious syndromes among development programs may obscure interrelationships of illness affecting those living in poor households—whether economic (e.g., as money spent on tobacco is lost from child health expenditures) or biological (e.g., as diabetes or HIV enhance the risk of tuberculosis). Please see later in the article for the Editors'' Summary     

Factors Contributing to Maternal and Child Mortality Reductions in 146 Low- and Middle-Income Countries between 1990 and 2010

Introduction

From 1990–2010, worldwide child mortality declined by 43%, and maternal mortality declined by 40%. This paper compares two sources of progress: improvements in societal coverage of health determinants versus improvements in the impact of health determinants as a result of technical change.

Methods

This paper decomposes the progress made by 146 low- and middle-income countries (LMICs) in lowering childhood and maternal mortality into one component due to better health determinants like literacy, income, and health coverage and a second component due to changes in the impact of these health determinants. Health determinants were selected from eight distinct health-impacting sectors. Health determinants were selected from eight distinct health-impacting sectors. Regression models are used to estimate impact size in 1990 and again in 2010. Changes in the levels of health determinants were measured using secondary data.

Findings

The model shows that respectively 100% and 89% of the reductions in maternal and child mortality since 1990 were due to improvements in nationwide coverage of health determinants. The relative share of overall improvement attributable to any single determinant varies by country and by model specification. However, in aggregate, approximately 50% of the mortality reductions were due to improvements in the health sector, and the other 50% of the mortality reductions were due to gains outside the health sector.

Conclusions

Overall, countries improved maternal and child health (MCH) from 1990 to 2010 mainly through improvements in the societal coverage of a broad array of health system, social, economic and environmental determinants of child health. These findings vindicate efforts by the global community to obtain such improvements, and align with the post-2015 development agenda that builds on the lessons from the MDGs and highlights the importance of promoting health and sustainable development in a more integrated manner across sectors.     

The history and control of the pine beauty moth, Panolis flammea (D. & S.) (Lepidoptera: Noctuidae), in Scotland from 1976 to 2000

1 The pine beauty moth, Panolis flammea, has been a serious pest of lodgepole pine plantations in Scotland since 1976. It historically feeds on native Scots pine throughout Europe but population levels of P. flammea on this host have never been high enough to cause tree mortality in the U.K. 2 This paper reviews recent advances in the biology of the pest and documents control programmes from 1976 to 1999. 3 There has been practically uninterrupted population monitoring of P. flammea from 1977 to the present day in Scottish lodgepole pine plantations. Intervention with chemical spraying has often been necessary. 4 The population data suggest that populations of P. flammea may have had a cyclic pattern over the monitoring period, with outbreaks occurring at regular intervals of between 6 and 7 years. 5 The amplitude of population cycles was large during the 1970s and 1980s, but has dampened in recent years. Natural enemies are believed to contribute to this trend. Fungal disease, specifically, appears to have had a greater effect on pest populations in recent years than in the past and is suggested to have contributed significantly to the population dynamics observed since 1990.     

Seasonal variation in natural mortality factors of Tuta absoluta (Lepidoptera: Gelechiidae) in open‐field tomato cultivation

The seasonal variation in natural mortality of phytophagous insects is determined by the relative importance of biotic and abiotic factors in agroecosystems. Knowledge regarding these factors throughout the year represents a key concern for IPM programmes. Seasonal population fluctuations of tomato pinworm, Tuta absoluta, led to an investigation of its natural mortality factors during the rainy season when the population level is low and during the dry season when population peaks occur. The aim of this study was to verify the seasonal variation in T. absoluta mortality factors in tomato crops. Immature stages of T. absoluta were obtained from laboratory‐rearing in the laboratory. These were taken to the field and monitored over two years. The mortality causes for each stage of insect development from egg to adult were assessed daily. Multiple biotic and abiotic mortality factors affected the immature T. absoluta stages such as rainfall, physiological disturbances, diseases, parasitoids and predators. The key T. absoluta mortality factor during summer–spring was predation. In addition, larvae predation correlated positively with temperature, wind velocity, photoperiod and rainfall. Nevertheless, during winter–fall, the key mortality factor was parasitism. Therefore, the critical stage for mortality was 3rd‐ and 4th‐instar larvae, being more vulnerable to natural control factors. Finally, the results showed the importance of vertical and horizontal action on natural mortality factors.     

Rodrigues fruit bats (<Emphasis Type="Italic">Pteropus rodricensis</Emphasis>, Megachiroptera: Pteropodidae) retain genetic diversity despite population declines and founder events

Fruit bats of the genus Pteropus are important contributors to ecosystem maintenance on islands through their roles as pollinators and seed dispersers. However, island faunas are the most prone to extinction and there is a real need to assess the possible genetic implications of population reductions in terms of extinction risk. An effective method of ameliorating extinction risk in endangered species is the establishment of captive populations ex situ. The effectiveness of captive breeding programmes may be assessed by comparing the genetic variability of captive colonies to that of wild counterparts. Here, we use polymorphic microsatellite loci to assess genetic variability in wild, critically endangered Rodrigues fruit bats (Pteropus rodricensis, Dobson 1878) and we compare this variability to that in a captive colony. We document remarkable conservation of genetic variability in both the wild and captive populations, despite population declines and founder events. Our results demonstrate that the wild population has withstood the negative effects of population reductions and that captive breeding programmes can fulfil the goals of retaining genetic diversity and limiting inbreeding.     

Constructing life-tables for the invasive maize pest Diabrotica virgifera virgifera (Col.; Chrysomelidae) in Europe

Abstract: The western corn rootworm (Diabrotica virgifera virgifera LeConte, Col.; Chrysomelidae) is an alien invasive species in Europe. It is a univoltine species with eggs that overwinter in the soil and larvae that hatch in spring. Three larval instars feed on maize roots, which can cause plant lodging and yield loss of economic importance. Adults emerge between mid‐June and early August and can reduce yields through intensive silk feeding. In order to provide a thorough understanding of the population dynamics of this invasive pest species in the invaded European region, complete age specific life‐tables were constructed in two maize fields in southern Hungary assessing the significance of natural mortality factors acting on D. v. virgifera populations. This information provides a rational basis for devising sustainable integrated pest management programmes, in particular, by enabling the identification of vulnerable pest age intervals for the timely application of various management tools. The life‐table for D. v. virgifera in Europe resulted in a total mortality of about 99% from the egg stage in the autumn to the emergence of adult females in the following year (K_Total = 2.48), which is comparable with North America. The highest reduction of D. v. virgifera numbers resulted from the mortality in first instar larvae (94% marginal death rate) and from the unrealized fecundity (80%). However, only the variation in mortality between years can change the generational mortality and thus influence population growth. High variation in the marginal death rate between fields and years was found in the second and third instar larval stages, and in the overwintering egg stage. These mortality factors therefore have the potential to cause changes in the total generational mortality. Furthermore, the life‐table suggested that a high fecundity could compensate for a high generational mortality and would lead to population increase.     

Combined use of the larvo‐pupal parasitoids Diachasmimorpha longicaudata and Aganaspis daci for biological control of the medfly

In biological control programmes, it is very common to employ multiple species to manage a single insect pest. However, the beneficial effects of natural enemies are not always additive because of several factors, including interspecific competition between these biocontrol agents. For this reason, in the present study we assessed several biological parameters (percentage parasitism, fertility, induced mortality and population reduction) of the parasitoids Diachasmimorpha longicaudata and Aganaspis daci when used together against the medfly Ceratitis capitata under laboratory and greenhouse conditions. Our results showed that, under laboratory conditions, fertility and percentage parasitism corresponded to a different functional response for each species (D. longicaudata: type II; A. daci: type III), whilst under greenhouse conditions, and unlike what occurs with single releases, both parasitoids showed a type III functional response; this is the only response which may lead to direct density dependence when host densities are low. Our results also revealed that when both species acted together, they produced a very high total percentage parasitism compared to that reported for single releases under both laboratory (64–76%) and greenhouse (21–51%) conditions. The parasitism was also higher for A. daci except when medfly larvae were provided in an artificial diet. Furthermore, host mortality induced by the two parasitoids acting together was very high, especially at low‐host densities; medfly population was almost completely reduced under greenhouse conditions. In summary, the data reported here supports the combined use of these species in biological control programmes against the medfly and highlights the importance of several factors, such as climatic conditions and host density, when planning their field releases.     

Protecting Free-Living Dormice: Molecular Identification of Cestode Parasites in Captive Dormice (Muscardinus avellanarius) Destined for Reintroduction

The success of any population translocation programme relies heavily on the measures implemented to control and monitor the spread of disease. Without these measures, programmes run the risk of releasing immunologically naïve species or, more dangerously, introducing novel infectious agents to native populations. As a precaution, a reintroduction programme for the common or hazel dormouse, Muscardinus avellanarius, in England screens dormice before release following captive breeding. Using PCR sequencing of a range of genes, we tested whether the same species of tapeworm(s) were present in captive and free-living dormice. Whilst only Rodentolepis straminea were identified in free-living dormice, cestode ova found in a captive individual produced a molecular match closely related to Hymenolepis microstoma and a previously unrecorded Rodentolepis species. To prevent putting at risk the free-living population, we recommended the continued treatment of dormice showing tapeworm infection before release. Our work demonstrates how molecular techniques can be used to inform reintroduction programmes, reduce risk from disease and increase chances of reintroduction success.

     

Estimating susceptibility of biological control agents to pesticides: influence of life history strategies and population structure

In this study we examined the influences that differing life history strategies and population structures at the time of pesticide exposure have on population susceptibility to pesticides. We used life table data and a matrix projection model to incorporate combinations of mortality (lethal effect) and reductions in fecundity (sublethal effect) into estimates of intrinsic population growth rates (r) for a predator, the seven-spot lady beetle, Coccinella septempunctata L., and its prey, the pea aphid, Acyrthosiphon pisum Harris, and an aphid parasitoid, Diaeretiella rapae (M’Intosh). All three species exhibited differences in key life history variables. The aphid had the highest r and shortest generation time, the ladybeetle had the lowest r and longest generation, while the parasitoid exhibited intermediate life history characteristics. When the model was run with populations started as neonates (aphids) or eggs (lady beetle, parasitoid) for each species, ladybeetle populations were much more susceptible than either aphid or parasitoid populations 30 days after simulated exposure to a pesticide. For example, 50% mortality and a 50% reduction in fecundity resulted in a population headed toward extinction (negative r) for the ladybeetle while the parasitoid population grew exponentially (positive r) even after sustaining 70% mortality and a 70% reduction in fecundity. The aphid species maintained exponential growth after sustaining 80% mortality and an 80% reduction in fecundity. Thus, differences in life history variables accounted for the greater susceptibility of the ladybeetle to a pesticide than its aphid prey or the parasitoid over a set time interval. These differences in susceptibility were greatly reduced when the model was run starting with a mixed age/stage population (the stable age distribution) for each species indicating that population structure at the time of pesticide exposure plays a critical role in population susceptibility. These results suggest that life history attributes as well as population structure at the time of pesticide exposure both play a major role in population susceptibility to pesticides, highlighting the need to explicitly consider differences in life history variables among species when calculating compatibility of pesticides and biological control agents as well as the population structure of beneficial species at the time of pesticide application.     

Are female reproductive status and male morphotypes of the giant freshwater prawn Macrobrachium rosenbergii altered by selection for high growth?

Understanding genetic changes in the hierarchical population structure of the giant freshwater prawn (GFP) Macrobrachium rosenbergii is important to improve productivity and profitability of prawn farming. We examined correlated responses in male morphotype and female reproduction status resulting from a selection programme for high growth in a GFP population undergoing four generations of selection. Two contemporary lines (selection and control) were maintained and produced simultaneously; the selection line was selected for high breeding values for harvest body weight and the control for average breeding values of the population. A total of 21,459 individual prawns were measured for body traits and morphotypes. Individual morphotype was recorded as a binary trait (0 and 1) and were analysed using a generalised threshold mixed model with a logit link function. Correlated genetic changes in three important male morphotypes (small, orange and blue claw males) were significant (p < 0.05–0.001) only in generation 2010 but not in the last generation (2012). Selection for high growth did not have an adverse effect on reproduction status of females, except that the selection line had a greater proportion of spawned females than the control (p = 0.01). Our results pointed out that selection for high growth may have had both positive and negative impacts on the social population structure of male morphotypes in GFP. Undesired changes in important morphotypes should be taken account of in genetic improvement programmes for GFP in order to minimise social competition effects and increase total biomass and consequently economic returns of the sector.     

Assessing footprints of selection in commercial Atlantic salmon populations using microsatellite data

Relatively large rates of response to traits of economic importance have been observed in different selection experiments in salmon. Several QTL have been mapped in the salmon genome, explaining unprecedented levels of phenotypic variation. Owing to the relatively large selection intensity, individual loci may be indirectly selected, leaving molecular footprints of selection, together with increased inbreeding, as its likely relatives will share the selected loci. We used population differentiation and levels of linkage disequilibrium in chromosomes known to be harbouring QTL for body weight, infectious pancreatic necrosis resistance and infectious salmon anaemia resistance to assess the recent selection history at the genomic level in Atlantic salmon. The results clearly suggest that the marker SSA0343BSFU on chromosome 3 (body weight QTL) showed strong evidence of directional selection. It is intriguing that this marker is physically mapped to a region near the coding sequence of DVL2 , making it an ideal candidate gene to explain the rapid evolutionary response of this chromosome to selection for growth in Salmo salar. Weak evidence of diversifying selection was observed in the QTL associated with infectious pancreatic necrosis and infectious salmon anaemia resistance. Overall, this study showed that artificial selection has produced important changes in the Atlantic salmon genome, validating QTL in commercial salmon populations used for production purposes according to the recent selection history.     

Influence of release size on establishment and impact of a root weevil for the biocontrol of houndstongue (Cynoglossum officinale)

The root-boring weevil, Mogulones cruciger, was introduced into Canada to control the weed, houndstongue (Cynoglossum officinale). To optimise its use as a biocontrol agent, a 2-year study was performed in British Columbia, Canada to test if the number of M. cruciger released at sites predicted subsequent declines in weed populations. No, 100, 200, 300 or 400 weevils were released in 1999 at field sites (five replicates) corresponding to discrete populations of houndstongue separated by distances of 0.3–3 km. The sites were subsequently monitored for weevil establishment, population change, and host attack, and houndstongue population change. By 2001, M. cruciger had established at all 20 release sites and was present in low numbers in three of five control sites. The year following release, release size was positively correlated with number of adult weevils collected, their damage to host plants, and with subsequent numbers of larvae per plant. In contrast, houndstongue populations were reduced at the same rate and amount, regardless of the experimental release size, within 2 years of release. Significant release treatment×time interactions indicated that factors other than M. cruciger contributed to houndstongue reductions (e.g. drought). However, overall the addition of weevils accelerated the reductions relative to sites with no weevils added. Our study demonstrated that the lowest number within a range of release sizes typically used in weed biocontrol programmes (i.e. 100) was as effective as 200–400 weevils in achieving a consistent amount and rate of houndstongue reduction, and thus, could be implemented to optimise weevil use and achieve predictable biocontrol.     

Mortality differentials within large American cities in 1890

This article presents a multiple regression analysis of demographic and social data for 335 wards in 17 American cities in 1890. The most important findings are: (1) Density effects on mortality were uniformly positive and statistically significant; the magnitude of these effects was much greater for child mortality than for adult mortality; and child mortality was more sensitive to persons per dwelling than to persons per acre. (2) Unsanitary conditions, as measured by the city-specific typhoid fever death rate, significantly increased mortality and child mortality was much more sensitive in this respect than adult mortality. (3) Given the same age composition and population density, foreign-born whites, native-born whites, and the colored population had about the same adult death rate.     

Density-dependent mortality of the human host in onchocerciasis: relationships between microfilarial load and excess mortality

Background

The parasite Onchocerca volvulus has, until recently, been regarded as the cause of a chronic yet non-fatal condition. Recent analyses, however, have indicated that in addition to blindness, the parasite can also be directly associated with human mortality. Such analyses also suggested that the relationship between microfilarial load and excess mortality might be non-linear. Determining the functional form of such relationship would contribute to quantify the population impact of mass microfilaricidal treatment.

Methodology/Principal Findings

Data from the Onchocerciasis Control Programme in West Africa (OCP) collected from 1974 through 2001 were used to determine functional relationships between microfilarial load and excess mortality of the human host. The goodness-of-fit of three candidate functional forms (a (log-) linear model and two saturating functions) were explored and a saturating (log-) sigmoid function was deemed to be statistically the best fit. The excess mortality associated with microfilarial load was also found to be greater in younger hosts. The attributable mortality risk due to onchocerciasis was estimated to be 5.9%.

Conclusions/Significance

Incorporation of this non-linear functional relationship between microfilarial load and excess mortality into mathematical models for the transmission and control of onchocerciasis will have important implications for our understanding of the population biology of O. volvulus, its impact on human populations, the global burden of disease due to onchocerciasis, and the projected benefits of control programmes in both human and economic terms.     

Correction: Overcoming Stagnation in the Levels and Distribution of Child Mortality: The Case of the Philippines

Background

Health-related within-country inequalities continue to be a matter of great interest and concern to both policy makers and researchers. This study aims to assess the level and the distribution of child mortality outcomes in the Philippines across geographical and socioeconomic indicators.

Methodology

Data on 159,130 children ever borne were analysed from five waves of the Philippine Demographic and Health Survey. Direct estimation was used to construct under-five and neonatal mortality rates for the period 1980–2013. Rate differences and ratios, and where possible, slope and relative indices of inequality were calculated to measure disparities on absolute and relative scales. Stratification was undertaken by levels of rural/urban location, island groups and household wealth.

Findings

National under-five and neonatal mortality rates have shown considerable albeit differential reductions since 1980. Recently released data suggests that neonatal mortality has declined following a period of stagnation. Declines in under-five mortality have been accompanied by decreases in wealth and geography-related absolute inequalities. However, relative inequalities for the same markers have remained stable over time. For neonates, mixed evidence suggests that absolute and relative inequalities have remained stable or may have risen.

Conclusion

In addition to continued reductions in under-five mortality, new data suggests that the Philippines have achieved success in addressing the commonly observed stagnated trend in neonatal mortality. This success has been driven by economic improvement since 2006 as well as efforts to implement a nationwide universal health care campaign. Yet, such patterns, nonetheless, accorded with persistent inequalities, particularly on a relative scale. A continued focus on addressing universal coverage, the influence of decentralisation and armed conflict, and issues along the continuum of care is advocated.     

Structural determinants of child mortality in sub‐Saharan Africa: A cross‐national study of economic and social influences from 1970 to 1997

Abstract

This cross‐national study seeks to understand the lagging child mortality declines in sub‐Saharan Africa by using World Bank data to investigate social and economic factors at three points in time: 1970, 1985, and 1997. Women's education, foreign debt‐to‐export ratio, and GNP per capita are among the strongest correlates of under five mortality over time. Cross‐sectional and longitudinal results suggest that female education is the best overall predictor of child mortality. Average national income does not emerge as a strong predictor, particularly since 1985. Increasing levels of foreign debt are associated with a substantial excess mortality burden. In 1997, the effect of adult HIV prevalence on child mortality was moderate and statistically significant. The study concludes that, although future gains in social factors such as female education will likely be beneficial, without simultaneously addressing high levels of foreign debt and high HIV prevalence, it may be difficult to improve child mortality rates across sub‐Saharan Africa.     

Ecological drivers of change at South Georgia: the krill surplus,or climate variability

Macaroni penguins Eudyptes chrysolophus are thought to be one of the most important mesopredators in the Southern Ocean having a greater impact on prey availability and abundance than any other seabird species. Their population centre has long been held to be South Georgia where populations were thought to comprise many million animals. Here we report the results of a recent census of the macaroni population at South Georgia undertaken using aerial survey methods. We report dramatic declines in numbers (～1.0 million breeding pairs) compared to numbers observed in the late 1970s (～5.4 million pairs), but show that these reductions have occurred principally at sites where numbers had previously been very large. During the breeding season, the main foraging grounds of birds from these sites overlap with the foraging grounds of Antarctic fur seals Arctocephalus gazella, a major competitor for their principal prey, Antarctic krill Euphausia superba. We suggest that the redistribution of the macaroni penguin population at South Georgia reflects the recent recovery of fur seal populations and thus the ongoing consequences of human intervention at South Georgia, a process which started more than 2 centuries previously. The implied resource competition and the observed population changes may also be exacerbated by recent reductions in Antarctic krill abundance which have been linked with reductions in seasonal sea ice following recent, rapid, regional warming in the Antarctic; however, the recovery of fur seal populations, and the ongoing recovery of krill‐eating whale populations argues that tropho‐dynamic interactions may be sufficient to explain the observed changes.